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BUG: KASAN: use-after-free in l2cap_chan_close+0x5c4/0x930 net/bluetooth/l2cap_core.c:734
Read of size 1 at addr ffff8880972c5020 by task kworker/1:2/2690

CPU: 1 PID: 2690 Comm: kworker/1:2 Not tainted 5.6.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events do_enable_set
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:374
 __kasan_report.cold+0x1a/0x32 mm/kasan/report.c:506
 kasan_report+0xe/0x20 mm/kasan/common.c:641
 l2cap_chan_close+0x5c4/0x930 net/bluetooth/l2cap_core.c:734
 do_enable_set+0x4cf/0x8e0 net/bluetooth/6lowpan.c:1074
 process_one_work+0x94b/0x1690 kernel/workqueue.c:2266
 worker_thread+0x96/0xe20 kernel/workqueue.c:2412
 kthread+0x357/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 3473:
 save_stack+0x1b/0x80 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:515 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:488
 kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 l2cap_chan_create+0x40/0x3a0 net/bluetooth/l2cap_core.c:446
 chan_create+0xc/0xd0 net/bluetooth/6lowpan.c:640
 bt_6lowpan_listen net/bluetooth/6lowpan.c:959 [inline]
 do_enable_set+0x511/0x8e0 net/bluetooth/6lowpan.c:1078
 process_one_work+0x94b/0x1690 kernel/workqueue.c:2266
 worker_thread+0x96/0xe20 kernel/workqueue.c:2412
 kthread+0x357/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 3473:
 save_stack+0x1b/0x80 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:337 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:476
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x109/0x2b0 mm/slab.c:3757
 l2cap_chan_destroy net/bluetooth/l2cap_core.c:484 [inline]
 kref_put include/linux/kref.h:65 [inline]
 l2cap_chan_put+0x1b2/0x230 net/bluetooth/l2cap_core.c:498
 do_enable_set+0x4db/0x8e0 net/bluetooth/6lowpan.c:1075
 process_one_work+0x94b/0x1690 kernel/workqueue.c:2266
 worker_thread+0x96/0xe20 kernel/workqueue.c:2412
 kthread+0x357/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8880972c5000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 32 bytes inside of
 2048-byte region [ffff8880972c5000, ffff8880972c5800)
The buggy address belongs to the page:
page:ffffea00025cb140 refcount:1 mapcount:0 mapping:ffff8880aa000e00 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002459088 ffffea0002526308 ffff8880aa000e00
raw: 0000000000000000 ffff8880972c5000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880972c4f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880972c4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880972c5000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff8880972c5080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880972c5100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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